Improvement in valve-gears for steam-engines



' section on the line 'UNITEDr STATES PATENT QFFICE" WILLIAM DENN ISON, OF WASHINGTON, DISTRICT OF COLUMBIA.

IMPROVEMENT IN VALVE-GEARS FOR STEAM-ENGlNES.

Specification forming part of Letters Patent No. 58,074, dated September 18, 18H3.

To all whom it may concern.-

Be it known that I, WILLIAM DENNIsoN, of .the city of Washington, in the District ot' Columbia, have invented a new and useful Improvelnent in the Manner of Operating the Valves of Steam-Cylinders 5 and I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the annexed drawings, making part ot' this speciiication, in which- Figure 1 is a side elevation of an engine, showing my improvement. Fig. 2 isa plan or top view of the same. Fig. 3 is a section on the line x m ot' Figs. l and 2.. Fig. 4 is a of Figs. l and 2.

A is a steamcylinder. ot' ordinary construction, resting on a bed-plate, B, and secured to it by bolts and nuts. C is the steam-chest, having a supply-opening at a and air escape at b. In Fig. 2 the top plate, c, of the steamchest is removed to show plainly the interior.

At each end of thesteam-chestis a concave, I) D', from the inner surface otl which open the steam ports and escape-channels. The steam-ports are in the bottom and centers ot' the concaves, while the escape-opening,trom one concave is on the opposite side ot the steam-port from the escapeopening in the other concave. These openings and their connections are shown in dotted lim-s, Figs. l, 2, and 4.

In each concave, and fitted steam-tight, is a block or 'valve, E E', having a chamber, d, Fig. 4, through which, when the valve is in a proper position, the steam may tlow from the cylinder into the escape opeilingsand channels. The valves E E are secured. by set-screws, or other devices, upon a rock shat`t, F, which passes through a stuttug-box in the front end of the steam-chest, and has its extreme forward end supported in a journal-box on the standard G.

The valves are so arranged upon the rockshaft as'that by its vibration the steam-ports are alternately opened to communication with the steam -ohest, and closed from it and opened to connect with the escape-openings through the chambers d in the valves.

The vibration ot' the rock-shaft is effected by means of the cam H, which is a segment of a cylinder grooved upon its convex face, as seen in dotted lines in Fig. 2 and in section in Fig. 3, firmly secured upon the rock-shaft.

Upon the piston-rod I, or upon the eros.

head 1, is a stud, K, projecting into the groove in the cam H.

Then the piston is at halt-stroke, as represented in the drawings, one ofthe steam-ports is wide open for the reception of steam from the steam-chest, while the other is connected with the escape.

As the piston-rod moves through the last half of the stroke the stud K acts against the sides ofthe groove, causing the cam to swing a distance equal to halt' the space between the two parts ot' the groove.

When the stroke has been completed the valve that was open has been shut and the other has commenced to open.

As the piston moves back the stud takes hold on the other part of the groove in the cam, swinging the valve more widely open, until the halt-stroke is made, when the action of the cam is reversed, as is also that of the valves.

Ido not intend tov contine myself to any particular form or degree of curvature of the grooves in the cam H, as different engines require different movements otl their valves; but the cam will be arranged to give such va.- rying movements ot` the valves as may be deemed most expedient.

The above-described arrangement ot) valves and of the cam with reference to the cylinder is applicable to water, air, and gas engines as well as to steam-engines, as described in the specification.

Having thus fully described my invention, what I claim as new therein, and desire to sccure by Letters Patent, is

1. The cam H, arranged to operate in such a way as to cause the valves of steam-cylinders to move continuously, while the piston ot' the steam-cylinder is in motion, by a stud or pin on the piston-rod, or other attachment producing the same result, substantially as set forth.

2. A steam-cylinder having its openings and valves arranged on a line with the axes of the cylinder, substantially in the manner set forth.

3. The cam H, the rock-shaft F, and the steam-cylinder, with its steam -valves E E', combined and operating as and for the purpose setforth. y

dlitiiesses: VILLIAM DENN ISON.

W. P. FEReUsoN, A. Nonne. 

